在 UserControl 中公开 DataGridView 的 columns 属性不能正常工作

Question

我将DataGridView 放在UserControl 中，并在我的用户控件中创建了一个公开datagridview 的columns 属性的公共属性。
这是示例代码：

public partial class UserControl1 : UserControl
{
    public UserControl1()
    {
        InitializeComponent();
    }

    public DataGridViewColumnCollection MyDataGridColumns
    {
        get
        {
            return dataGridView1.Columns;
        }
    }
}

然后我在表单中添加UserControl1，然后在属性窗口中单击MyDataGridColumns 属性并添加1 列或更多列。 问题发生在我重建解决方案时；我刚刚添加的所有列在重建后都会消失。

谁能向我解释为什么会发生这种情况？以及如何解决？

Answer 1

这对我有用：我创建了一个特定的列编辑器，因为似乎不可能对任何不扩展 DataGridView 的控件使用默认列编辑器。

public partial class UserControl1 : UserControl, IDataGridView
{
    public UserControl1()
    {
        InitializeComponent();
    }

    [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
    [Browsable(false)]
    public DataGridView DataGridView
    {
        get { return dataGridView1; }
    }

    [DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
    [Editor(typeof(ExtendedDataGridViewColumnCollectionEditor), typeof(UITypeEditor))]
    [MergableProperty(false)]
    public DataGridViewColumnCollection MyDataGridColumns
    {
        get { return dataGridView1.Columns; }
    }

}

public interface IDataGridView
{
    DataGridView DataGridView { get; }
}

class ExtendedDataGridViewColumnCollectionEditor : UITypeEditor
{
    private Form dataGridViewColumnCollectionDialog;

    private ExtendedDataGridViewColumnCollectionEditor() { }

    private static Form CreateColumnCollectionDialog(IServiceProvider provider)
    {
        var assembly = Assembly.Load(typeof(ControlDesigner).Assembly.ToString());
        var type = assembly.GetType("System.Windows.Forms.Design.DataGridViewColumnCollectionDialog");

        var ctr = type.GetConstructors(BindingFlags.NonPublic | BindingFlags.Instance)[0];
        return (Form)ctr.Invoke(new object[] { provider });
    }

    public static void SetLiveDataGridView(Form form, DataGridView grid)
    {
        var mi = form.GetType().GetMethod("SetLiveDataGridView", BindingFlags.NonPublic | BindingFlags.Instance);
        mi.Invoke(form, new object[] { grid });
    }

    public override object EditValue(ITypeDescriptorContext context, IServiceProvider provider, object value)
    {
        if (provider != null && context != null)
        {
            var service = (IWindowsFormsEditorService)provider.GetService(typeof(IWindowsFormsEditorService));
            if (service == null || context.Instance == null)
                return value;

            var host = (IDesignerHost)provider.GetService(typeof(IDesignerHost));
            if (host == null)
                return value;

            if (dataGridViewColumnCollectionDialog == null)
                dataGridViewColumnCollectionDialog = CreateColumnCollectionDialog(provider);

            //Unfortunately we had to make property which returns inner datagridview  
            //to access it here because we need to pass DataGridView into SetLiveDataGridView () method 
            var grid = ((IDataGridView)context.Instance).DataGridView;
            //we have to set Site property because it will be accessed inside SetLiveDataGridView () method 
            //and by default it's usually null, so if we do not set it here, we will get exception inside SetLiveDataGridView () 
            var oldSite = grid.Site;
            grid.Site = ((UserControl)context.Instance).Site;
            //execute SetLiveDataGridView () via reflection 
            SetLiveDataGridView(dataGridViewColumnCollectionDialog, grid);

            using (var transaction = host.CreateTransaction("DataGridViewColumnCollectionTransaction"))
            {
                if (service.ShowDialog(dataGridViewColumnCollectionDialog) == DialogResult.OK)
                    transaction.Commit();
                else
                    transaction.Cancel();
            }
            //we need to set Site property back to the previous value to prevent problems with serializing our control 
            grid.Site = oldSite;
        }

        return value;
    }

    public override UITypeEditorEditStyle GetEditStyle(ITypeDescriptorContext context)
    {
        return UITypeEditorEditStyle.Modal;
    }
}

Answer 2

这是因为您没有指定列的类型。添加列时应提供列的类型（例如DataGridViewTextBoxColumn 或DataGridViewCheckBoxColumn）。在您的 Form1.cs 中执行以下操作：

public Form1()
{
    InitializeComponent();
    DataGridViewColumn dgViewColumn = new DataGridViewTextBoxColumn();//Or DataGridViewCheckBoxColumn
    dgViewColumn.DataPropertyName = "dgViewColumn";
    dgViewColumn.HeaderText = @"dgViewColumn";
    dgViewColumn.Name = "dgViewColumn";
    userControl11.MyDataGridColumns.Add(dgViewColumn);
}

Answer 3

@Bioukh answer works in VS2019 and somewhat works in VS2022。但是，在我的 UserControl 中嵌入 DataGridView 控件然后使用 answer 添加和编辑列的结果不会使这些列迁移 到 UserControl 的另一个实例。例如：复制/粘贴 UserControl，所有嵌入的 DataGridView 的列都会从新副本中消失。

为了解决这个问题，我将我的 DataGridView 实例维护为 native，并在我的 UserControl 中使用公共 DataGridView 属性，并在属性设置器中执行绑定和对接。然后我将 my_UserControl 放在我的表单上，将 my_DataGridView 放在我的表单上，然后设置 my_UserControl.DataGridView = my_DataGridView。此解决方法保留了与 DataGridView 关联的本机属性和行为。

在 my_UserControl 中，我有一个名为“GridPanel”的 Panel 和一个 VScrollBar。然后我添加了以下属性：

///<summary>
/// Associates a native DataGridView with this UserControl
/// then sets the DataGridView.Parent to the Panel in this UserControl
/// and sets the DataGridView.Dock to Fill the Panel
///</summary>
public DataGridView? ContainedDataGridView
{
  get
  {
    try
    {
      // if we have a DataGridView in our Panel then return it
      if ((this.GridPanel.Controls.Count == 1)
          && (this.GridPanel.Controls[0] is DataGridView view))
      {
        return view;
      }
    }
    catch (Exception ex)
    {
      //// TODO Handle "ContainedDataGridView get error"
    }

    // Return null if there is no DataGridView or there was an error checking for it.
    return null;
  }
  set
  {
    try
    {
      // Clear the panel to prevent adding more than one DataGridView
      this.GridPanel.Controls.Clear();

      if (value is not null)              
      {
        this.GridPanel.Controls.Add(value);
        value.Parent = this.GridPanel;
        value.Dock = DockStyle.Fill;
      }
      // else the panel remains cleared
    }
    catch (Exception ex)
    {
      //// TODO Handle "ContainedDataGridView set error"
    }
  }
}

上述 sn-p 编码为 C# 10、.NET 6、Windows Forms App、UserControl 并在 Visual Studio 2022 版本 17.0.3 中测试